The invention relates to a push-pull amplifier as described in the pre-amble of claim 1. The invention further relates to a demodulation filter for use in a push-pull amplifier.
From European Patent application EP-A-0776088 an amplifier output stage is known having a demodulation filter. Herein a demodulation filter comprises inductances and capacitances to demodulate the signal before supplying to a load, for example a loudspeaker.
Further from a publication xe2x80x9cA review and Comparison of Pulse Width Modulation (PWM) Methods For Analog and Digital Switching Power Amplifiersxe2x80x9d of K. Nielsen 102 AES Convention, Munich March 1997, Preprint 4446 also a demodulation filter is known.
A disadvantage of such an amplifier and demodulation filter is that the described demodulation filter operates for common mode signals as an oscillating loop, and has a peaking in the common mode operation.
It is an object of the invention to provide a push-pull amplifier not having these disadvantages. To this end a push-pull amplifier according to the invention comprises the features of claim 1.
The demodulation filter according to the invention overcomes these disadvantages by introducing a common mode damping without influencing the differential mode.
The invention further relates to a demodulation filter for use in such a push-pull amplifier.
Further embodiments of the invention are described in the dependent claims.
Herewith a cross-reference is made to the following co-pending applications of the same applicant and of the same date:
xe2x80x9cCarrousel handshakexe2x80x9d applicant""s ref. Nr. ID603908, Application No. 0 201 818.2
xe2x80x9cLevel shifterxe2x80x9d applicant""s ref. Nr. ID604680, Application No. 0 201 826.5
xe2x80x9cSilent startxe2x80x9d applicant""s ref. Nr. ID604681, Application No. 0 201 827.3
xe2x80x9cPWM limiterxe2x80x9d applicant""s ref. Nr. ID604682, Application No. 0 201 828.1.